Session: 01-06-03: Impact, Fatigue, Damage and Fracture of Composite Structures

Paper Number: 109313

109313 - Analysis of the Effects of Welding Induced Residual Stress on Fatigue Crack Growth of Welded Joints 

Welding is a widely used permanent joining technology in the manufacturing and connecting of mechanical constructions such as pressure vessels, ships, and bridges. There are different factors that contribute to the fatigue life of welded joints. These factors can be divided into two. Specifically, intrinsic characteristics include geometrical discontinuity, weld defect, welding induced residual stress, thermomechanical property, and the elastic-plastic behavior of welded joints. Intrinsic factors include stress ratio, loading modes, and operating environment. Residual stresses in welded components result from heterogeneous plastic deformations during the welding thermal cycle. The thermal field produced by the welding process, combined with temperature-dependent material properties, causes local expansion and contraction that is limited by less temperature-affected material volumes. Locally hindered shrinkage causes tensile residual stresses during cooling, and hindered expansion from phase transformation results in local compressive residual stresses. Welding induced residual stress can affect the fatigue and creep lifetime of the welded joint by reducing the fatigue and creep lifetime of the welded joint, which can change the crack tip profile of the welded joint. The magnitude of welding-induced residual stress is determined by the amount of heat input during the welding process, and a large amount of residual stress results from a high heat input. The purpose of this study is to show the effects of welding induced residual stresses on the behavior of fatigue crack growth (FCG) in welded joints. Furthermore, the redistribution of welding residual stresses during fatigue was investigated, as was the effect on fatigue life. It was possible to model the heat source using an analytical approach in a way that corresponded to the result of the actual heat source; the model is based on types of approximation or simplification of reality, with some discrepancy that is possible and did occur. The crack direction is investigated when estimating the stress intensity factor (KI ) for a welded joint using an analytical method. The results show that depending on the stress distribution, welding residual stress can either increase or decrease the stress intensity factor and indicate the effects of residual stress and fracture direction on the stress intensity factor.

Presenting Author: YAHIYA AHMED KEDIR University of Stavanger

Presenting Author Biography: I am an expert in mechanical design. a mechanical design specialist with extensive experience in mechanical system design and the ability to use a variety of engineering software. Research area: modeling of fatigue crack initiation and growth of mechanical structures master's thesis title is "Numerical modeling of fatigue crack growth of the welded joint at elevated temperatures." It requires making a computer program and a 3D CAD model that can be simulated using the finite element method in ABAQUS, MATLAB, and analytical methods. Currently I’m studying PhD in Mechanical Design at University of Stavanger, Faculty of Science and Technology, N-4036 Stavanger, Norway

Authors:

YAHIYA AHMED KEDIR University of Stavanger